BONN, Dec 7 (Reuters) - Germany is set to expand its
onshore wind power capacity by 1.7 gigawatts (GW) a year up to
2032, its Federal Network Agency said on Wednesday after
studying the impact of a planned rapid expansion of green power
in Europe's biggest economy.

It would arrive at 47.5 GW in 2022 and 64.5 GW in 2032,
compared with 27.1 GW of capacity installed in 2010, the
agency's president Matthias Kurth said at a news briefing.

The authority, which supervises grids, said it looked
realistic that fledgling offshore wind capacity could reach 13
GW in 2022 and 28 GW in 2032.

Solar power may reach 54 GW in 2022 and 65 GW in 2032, it
said.

The figures are important to gauge subsidy levels for
renewable power, which under German law must be shared by all
consumers, the requirements for transmission grid expansion, and
for future network stability, given that renewables are volatile
as a power source.

"We are describing what we would need so that we can say
that in 10 years' time, we will have secure supply and
networks," Kurth said.

Germany has embarked on a strategy shift away from
fossil-fuels based production towards green power, and Kurth has
a brief to commit transmission firms and generators to ensure
the right infrastructure is installed in a coordinated fashion.

Wednesday's data will serve as the basis for plans the
transmission firms must present next June, in order for the
government to finalise grid expansion laws from 2013.

TOP LOAD, DEMAND SEEN STEADY

The maximum load on the high-voltage grids - reflecting top
demand - was assumed to remain steady at 84 GW in a scenario up
to 2022 and German power demand was assumed to be steady at
535.4 terawatt hours (TWh), the agency said.

These are sensitive figures as Germany's hasty decision this
year to abandon nuclear energy earlier than planned was feared
to be causing stress on networks at high demand times and when
renewable supply is not available due to weather patterns.

Despite zero fuel input and no carbon emissions, the problem
with renewablespower is that without the right weather, there
may not be enough production when needed.

Power cannot yet be stored in great amounts and Kurth said
that prospects for effective solutions were 20 to 30 years away.

The stable demand figure up to 2022 was based on the
assumption that energy efficiency gains would offset consumption
increases arising from economic growth, he said.

The stable load figure hinged on assumptions that better
grid usage and management, and new cables, will help rein in
potential overloads or disruptive load swings on the grids.

More short term, Kurth reiterated that this and next winter
looked supplied enough to cope with the loss of a huge slice of
nuclear energy earlier this year, when Germany shut its oldest
reactors in the wake of the Fukushima disaster.

The Bundesnetzagentur in August made provisions for
coal-fired plants to rev up capacity at times of undersupply
after off 41 percent of Germany's former nuclear capacity was
switched off permanently.

"We have said we should keep a handle on the situation and
there are no renewed doubts," Kurth said.
(Editing by William Hardy)